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*参照元 [#m3c8a59c] #backlinks *説明 [#gea8c424] -パス: [[linux-4.4.1/include/media/videobuf2-core.h]] -FIXME: これは何？ --説明 **参考 [#h73c525f] *実装 [#z603c67a] /** * struct vb2_ops - driver-specific callbacks * * @queue_setup: called from VIDIOC_REQBUFS and VIDIOC_CREATE_BUFS * handlers before memory allocation, or, if * *num_planes != 0, after the allocation to verify a * smaller number of buffers. Driver should return * the required number of buffers in *num_buffers, the * required number of planes per buffer in *num_planes; the * size of each plane should be set in the sizes[] array * and optional per-plane allocator specific context in the * alloc_ctxs[] array. When called from VIDIOC_REQBUFS, * fmt == NULL, the driver has to use the currently * configured format and *num_buffers is the total number * of buffers, that are being allocated. When called from * VIDIOC_CREATE_BUFS, fmt != NULL and it describes the * target frame format (if the format isn't valid the * callback must return -EINVAL). In this case *num_buffers * are being allocated additionally to q->num_buffers. * @wait_prepare: release any locks taken while calling vb2 functions; * it is called before an ioctl needs to wait for a new * buffer to arrive; required to avoid a deadlock in * blocking access type. * @wait_finish: reacquire all locks released in the previous callback; * required to continue operation after sleeping while * waiting for a new buffer to arrive. * @buf_init: called once after allocating a buffer (in MMAP case) * or after acquiring a new USERPTR buffer; drivers may * perform additional buffer-related initialization; * initialization failure (return != 0) will prevent * queue setup from completing successfully; optional. * @buf_prepare: called every time the buffer is queued from userspace * and from the VIDIOC_PREPARE_BUF ioctl; drivers may * perform any initialization required before each * hardware operation in this callback; drivers can * access/modify the buffer here as it is still synced for * the CPU; drivers that support VIDIOC_CREATE_BUFS must * also validate the buffer size; if an error is returned, * the buffer will not be queued in driver; optional. * @buf_finish: called before every dequeue of the buffer back to * userspace; the buffer is synced for the CPU, so drivers * can access/modify the buffer contents; drivers may * perform any operations required before userspace * accesses the buffer; optional. The buffer state can be * one of the following: DONE and ERROR occur while * streaming is in progress, and the PREPARED state occurs * when the queue has been canceled and all pending * buffers are being returned to their default DEQUEUED * state. Typically you only have to do something if the * state is VB2_BUF_STATE_DONE, since in all other cases * the buffer contents will be ignored anyway. * @buf_cleanup: called once before the buffer is freed; drivers may * perform any additional cleanup; optional. * @start_streaming: called once to enter 'streaming' state; the driver may * receive buffers with @buf_queue callback before * @start_streaming is called; the driver gets the number * of already queued buffers in count parameter; driver * can return an error if hardware fails, in that case all * buffers that have been already given by the @buf_queue * callback are to be returned by the driver by calling * @vb2_buffer_done(VB2_BUF_STATE_QUEUED). * If you need a minimum number of buffers before you can * start streaming, then set @min_buffers_needed in the * vb2_queue structure. If that is non-zero then * start_streaming won't be called until at least that * many buffers have been queued up by userspace. * @stop_streaming: called when 'streaming' state must be disabled; driver * should stop any DMA transactions or wait until they * finish and give back all buffers it got from buf_queue() * callback by calling @vb2_buffer_done() with either * VB2_BUF_STATE_DONE or VB2_BUF_STATE_ERROR; may use * vb2_wait_for_all_buffers() function * @buf_queue: passes buffer vb to the driver; driver may start * hardware operation on this buffer; driver should give * the buffer back by calling vb2_buffer_done() function; * it is allways called after calling STREAMON ioctl; * might be called before start_streaming callback if user * pre-queued buffers before calling STREAMON. */ struct vb2_ops { int (*queue_setup)(struct vb2_queue *q, const void *parg, unsigned int *num_buffers, unsigned int *num_planes, unsigned int sizes[], void *alloc_ctxs[]); - --[[linux-4.4.1/vb2_queue]] void (*wait_prepare)(struct vb2_queue *q); void (*wait_finish)(struct vb2_queue *q); int (*buf_init)(struct vb2_buffer *vb); int (*buf_prepare)(struct vb2_buffer *vb); void (*buf_finish)(struct vb2_buffer *vb); void (*buf_cleanup)(struct vb2_buffer *vb); - --[[linux-4.4.1/vb2_buffer]] int (*start_streaming)(struct vb2_queue *q, unsigned int count); void (*stop_streaming)(struct vb2_queue *q); void (*buf_queue)(struct vb2_buffer *vb); }; *コメント [#b363b256]
